热声制冷机声功耗散机理及变截面抑制方法研究

Thermoacoustic refrigerator is a new type of refrigerator with many advantages such as no moving parts, no pollution, which makes it with great development potential and application prospect. But there are many acoustic power dissipative effects which greatly restrict the improvement of refrigeration efficiency. The resonator with variable cross-section can suppress the dissipative effects such as shock wave, high order harmonic. However, there is still a lack of theoretical guidance for how to design the optimal tube type to suppress acoustic power dissipation. For these purposes, the project conducts numerical simulation on the acoustic power dissipative mechanism in thermo- acoustic refrigerator and its suppression methods by variable cross-section tube. The specific contents are followed as: (1) Establishing the nonlinear multi-dimension model for acoustic resonator with arbitrary shape basing on the gas-kinetic scheme. Moreover, verifying and correcting the model by theory and experiment; (2) Investigating the characteristics of nonlinear acoustic flow field in resonator with different shapes and under different acoustic excitation. Analysing the law of acoustic flow field characteristic quantity which is used to describe the dissipative phenomena, and analysing the effects of tube type parameters as well as acoustic excitation on acoustic flow field characteristic quantity, and then, establishing the relation between acoustic power dissipative effects and tube type parameters as well as acoustic excitation. At last, revealing the intrinsic mechnisms of the acoustic power dissipative effects in these resonators; (3) Exploring the role and capacity of resonator shapes in suppressing or decreasing these dissipative phenomena, and obtaining a theoretical foundation for tube type optimization design aiming to reduce the dissipation of acoustic power and enhance the output power. Some theoretical guidances and data supports will be provided for the design of efficient thermoacoustic refrigerator by the present project.

热声制冷机具有无运动部件、环保等优点，是一种极具发展潜力和应用前景的新型制冷机。但声功耗散严重限制了其效率的提高。变截面谐振管可以抑制激波、高次谐波等声功耗散效应。但是，目前尚缺乏抑制声功耗散的管型优化设计理论依据。为此，项目拟开展关于热声制冷机声功耗散机理及变截面抑制方法的模拟研究，具体的：(1)基于气体动理学方法，建立适合模拟任意形状声谐振管的非线性高维分析模型，理论及实验验证并完善模型；(2)模拟研究不同激励声源下、不同形状声谐振管内的非线性声流场特性，分析描述各耗散现象的声流场特征量及其变化规律，分析管型参数、激励声源对声流场特征量的影响，建立耗散现象与管型参数、激励声源之间的联系，揭示各耗散现象的本质机理；(3)探索不同形状谐振管在抑制或减少这些耗散现象方面的作用和能力，获得声功耗散最小、输出功率最大的管型优化设计依据。本项目将为高效的热声制冷机的设计提供理论依据和数据支持。

热声制冷机具有无运动部件、环保等优点，是一种极具发展潜力和应用前景的新型制冷机。但声功耗散严重限制了其效率的提高。变截面谐振管可以抑制激波、高次谐波等声功耗散效应。但是，目前尚缺乏抑制声功耗散的管型优化设计理论依据。为此，项目开展了关于热声制冷机声功耗散机理及变截面抑制方法的模拟研究，主要研究内容为：(1)基于气体动理学方法，建立适合模拟任意形状声谐振管的非线性高维分析模型，理论及实验验证并完善模型；(2)模拟研究不同激励声源下、不同形状声谐振管内的非线性声流场特性，分析描述各耗散现象的声流场特征量及其变化规律，分析管型参数、激励声源对声流场特征量的影响，建立耗散现象与管型参数、激励声源之间的联系，揭示各耗散现象的本质机理；(3)探索不同形状谐振管在抑制或减少这些耗散现象方面的作用和能力，获得声功耗散最小、输出功率最大的管型优化设计依据。项目研究过程中获得了如下的重要结果及关键数据：1）建立了变截面声谐振管非线性高维分析的气体动理学模型；2）对大幅值声振荡下各非线性耗散现象进行了机理分析；3）研究了指数型热声谐振管谐振频率的变化规律；4）模拟研究了指数型热声谐振管内非线性声流场；5）分析了指数型热声谐振管内耗散现象及其形成机理；6）分析了指数型热声谐振管内耗散现象的影响因素；7）开发了一种简单、有效、计算量少、普适性强的变截面热声谐振管本征频率计算方法；8）分析了几何形状对热声谐振管谐振频率、压力放大比及其性能的影响；9）以压力放大比为目标函数，获得了几种常见管型的最优管形参数。本项目的研究实现了气体动理学方法在热声模拟中的应用，为复杂热声系统和实用装置的开发提供了新的数值分析方法，同时也为高效的热声制冷机的设计提供理论依据和数据支持。